1. Field of the Invention
The present invention relates to the encoding and transmission of signals from a plurality of sources, such as video or audio sources.
2. Description of the Related Art
Television signals are transmitted using encoders, which compress the data prior to transmission, enabling more data to be transmitted at higher speeds. The higher speeds can be accomplished by a single encoder or a plurality of encoders having a modular structure. The encoders process the information on many parallel paths, such as paths for one or more video signals, audio signals, data which describes the encoder state, etc.
Transmission systems typically use codes having variable lengths. When the number of video samples present in the time unit at the encoder input includes a highly variable field, it is suitable to have a modular structure, such as, for example, in the encoding of high definition television signals (HDTV), in which the generation speed of samples can exceed 100 MHz (interleaved scanning) or 200 MHz (progressive scanning). When the information is processed using a plurality of parallel paths, it is necessary to organize the data such that the path from which the data was transmitted can be determined at the reception side so that the decoder can properly decode the data.
When encoders are used to compress data prior to transmission, variable length codes adapt the data flow to the complexity of data from the source. Variable length codes also enable encoding of equal word sequences of variable length words. In these cases, the data generation speed varies greatly over time.
The variation occurs in each of the plurality of processing paths. In practice, each path operates as a data source having a different speed variation over time. The data must be properly combined for effective transmission.